Increases in data transfer rates throughout a network may lead to unexpected issues when network components are not configured to handle the increased speeds. For example, existing customer premise equipment (CPE) may be upgraded with a top-tier configuration file from, for example, 100 Mbps to 300 Mbps, however, as a result of the upgrade, throughput at legacy devices (e.g., legacy 100Base-T Ethernet gear) may have their throughput drop while using TCP (transmission control protocol) applications. This issue can result from a network problem that occurs when a big pipe meets a little pipe (e.g., a 300 Mbps pipe flowing into a 100 Mbps pipe). For example, the situation may arise where more than 100 Mbps of network traffic ingresses into an Ethernet switch and the only egress is a 100 Mbps port. Thus, the Ethernet switch is forced to drop packets internally once its internal buffers are exhausted. These dropped packets result in the TCP receiver repeatedly acknowledging the last received segment until the sender detects this and determines there is a congestion situation. TCP will take over and start adjusting the transmission down to automatically avoid congestion. In this case it ends up adjusting the transmission down to a point where the entire link is not optimally used. The bursty DOCSIS (data over cable service interface specification) upstream combined with the buffer depth in the switch itself may lead to the observed issues.
This is a situation that can be alleviated if the network could be informed of backpressure using pause frames which are defined by the 802.3x standard. With pause frames enabled in the switch, when it detects that it is out of buffers it can send pause frames back toward the big pipe and those frames tell the big pipe to stop transmitting for a specified amount of time. However, there is a downside to pause frames and that is head-of-line blocking. Pause frames go back up the GigE port of the external switch into the modem's internal layer-2 switch. These pause frames tell the layer-2 switch to stop transmitting on that port for a predetermined or specified time. This causes the layer-2 switch to buffer packets until it runs out of buffers. Backpressure is then realized in the DOCSIS layer when the switch sees that the layer-2 switch buffers are exhausted. DOCSIS will then start buffering the data packets. The problem is that all data flows going through the layer-2 switch of the modem are slowed down, which is used to connect various other interfaces such as Ethernet, MoCA (multimedia over coax alliance), Wi-Fi, and others. Therefore, a need exists for improving methods and systems for dynamically controlling the output of pause frames.
Like reference numbers and designations in the various drawings indicate like elements.